Lapping apparatus



Dec. 1o, 1946. R. Smm.

LAPPINGAPPARATUS Filed Aug. 25, 1944 /NVENTo/a E. STGLL.

'- 0 BY AW' HTTORNEY Patented' Dec. 10, 1946 LAPPINGAPPARATUS B ,einhold Stoll, Elgin, Ill., asslgnor to Western Electric' Company, Incorporated, New York, N. Y., a corporation of New York Application August 25, 1944, Serial No. 551,188

11 Claims.

This invention relates to a lapping apparatus and more particularly to an apparatus for lapping thin parts, such as feeler gages.

In lapping parts like feeler gages, dimculty has been experienced in securing flat and parallel faces on said parts when they are not perfectly dat before lapping. A curved or bowed part may be lapped to a desired thickness, but, when removed from the lapping machine, may resume its bowed shape, which may nullify its usefulness.

An object of the present invention is to provide an ede'ctive lapping device for accurately lapping parte.

In accordance with one embodiment oi the invention, there is provided a stationary lower lapping member and a movable upper lapping member resting thereupon and spaced therefrom by a plurality of adjustable supports capable of being worn away and supporting the upper lapping member to prevent undue pressure on a part to be lapped in the initial stages of thelapping operation, the supports wearing away as vthe` lapping of the part proceeds.

The invention will be more fully understood from the following description taken in conjunction with the accompanying drawing illustrating one embodiment thereof, in which Fig. l is a perspective view of the lapping apparatus';

Fig. 2 is a vertical cross' section of the lapping apparatus taken on the line 2-2 of Fig. l; and

Fig. 3 is a bottom plan view of the upper lapping member.

Referring to the drawing, there is shown a lower stationary lapping member i@ having a flat lapping surface II provided with parallel longitudinal and transverse scoring I 2. An upper lapping member i@ is rectangular in shape and of substantial thickness to provide a weight' sumcient to exert the necessary downward force during the lapping operation. The lapping member Id has a nat lapping surface I5 provided with parallel longitudinal and lateral scoring I6 therein. A plurality of threaded apertures Il are provided in the upper lapping member, one adjacent each corner thereof, the lower ends oi which'are enlarged, as at I8, to receive cylindrical supporting members or studs `2li of equal hardness. 'I'he studs 20 tightly engage the walls of the apertures I8` and are adjustable therein and held in adjusted position by adjusting screws 2| engaging the threaded apertures II.

l The studs 20 are adapted to project beyond the lapping surface I5 and engage the surface II of the lower lapping member 10, thereby supporting the-upper lapping member so that its lapping surface I5 is spaced a distance from the lower lapping surface Il equal to the length of the 'slight bow or curvature.

2 portion of the stud projecting from said surface Il.

Retaining plates or members 24 are secured to the sides of the upper lapping member I4 by screws 25, which pass through enlarged apertures 26 therein. The retaining plates extend downwardly beyond the lower surface I5 of the member I6 and extend across the length and width thereof to form a retaining well or rim around the lower edge of the member I4, which rim is spaced from the lower lapping surface II to provide clearance sufficient to permit the lapping of the work. This rim serves to retain the parts being lapped between the lapping surfaces. An aperture 2i is provided in Ithe upper lapping member id for the reception of one end of a crank 'it of a suitable rotary device for imparting a rotary motion to the lapping member it or, if desired, the lapping member It may be operated manually.

In the operation of the lapping apparatus, all the studs iii are accurately adjusted so that the projecting ends extend out from the lapping surface I5 a distance equal to or slightly in excess of the overall thickness of the part to be lapped, which may include the thickness of the part, plus any deformations or irregularities, such as a The upper lapping member is removed from the lower lapping member and the workto be lapped as, for example, the part 3G, is placed thereon and the upper lapping member it is positioned over it. The overall distance between the` two parallel lapping faces i5 and ii will be equal to or in excess of the vertical dimension from the plate II to the uppermost portion of the part 30. The lapping member ifi may then be moved in a rotary motion, either manually or yby connecting it to a driven crank for automatic operation. As the lapping member ifi moves on the lower lapping member, it will move relative to the work 30 and when moved far enough, the retaining rim 2l thereon will engage the work 30 and move it relative to the lower member l0. At the same time, the contacting surfaces of the studs,2|l will wear away evenly and permit the lapping member I 4 to move downwardly while maintaining its parallel relation to the member I0. As the studs 20 are worn away and the part 30 moves relative to lthe upper and lower members, the upper lapping surface i5 will engage the high spots on the upper surface and Vlap them away and the lower lapping surface II will lap away the high spots on the underneath side of the part 30 without any undue pressure being exerted on the part 30. The lapping operation is continued until the part has been lapped to the required dimension. Thus, the lapping of the part 30 is accomplished with a pressure which is insuiiicient to cause deforming or flattening of said part dur-'- ing the lapping thereof.. If desired, twojiorsmore (member in a plane/parallel to one of said lapping surfaces and means associated withone of said members and 'engaging the other member for separating saidmembers a predetermined distance and gradually reducing the distance therebetweenas the lapping operation proceeds.

2. A lapping apparatus comprising a stationary lapping member, a movable lapping member, each of said lapping members having a lapping surface thereon, means for moving said movable lapping member in'a plane parallel to oneof said lappingsurfaces means associated with one of said members and engaging thev other member for separating said members a predetermined distance and gradually reducing the distance therebetween as the lapping operation proceeds', and means associated with one of said lapping members for confining a work piece within the lapping'area of said lapping member and movinar it relative to said other member.

3. A lapping apparatus comprising a stationary lapping member having a lapping surface, a, movable lapping member having a lapping surface and being movable on the lapping surface of said stationary lapping member during a lapping ping surface of said stationary' lapping member during a lapping operation, and a plurality-of adjustablesupports capable of .being worn away during the-lapping operation associated ywith the movable lapping member and engaging the lapn ping surface) of the stationary lapping member for providing a' predetermined varying spacing between said members as said supports are worn away.

7. A lapping apparatus comprising astationary lapping member, a movable lapping member, a]

plurality of adjustable supports capable of being dWorn away associated withV the movable lapping vmember and engaging the stationary lapping i rality of adjustable supporting members capable operation, and a plurality of supports capable of being worn away during the lapping operation 'projecting from onepf said members and engaging the lapping surface of the other member for providinga predetermined varyingspacing between said members as said supports'are worn away.

4. A lapping apparatus comprising a stationary lapping member having a lapping surface, a

movable lapping member having a lapping surface and being movable on the lapping surface of said stationary lapping member during a lapping operation, a plurality of adjustable supports capable of being worn away during the lapping operation projecting from one of said members and engaging the lapping surface of the` other member for providing a predetermined varying spacing between said members as said supports are worn away, and means for adjusting the supporting members to initially space said lapping members.

5. A lapping apparatus comprising a stationary lapping member having a lapping surface, a movable lapping member having a lapping surface and being movable on the lapping surface of being worn away during the lapping operation projecting from said lapping member to*` engage projecting from said lapping member to engage the lapping surface of the lapping plate and to provide a predetermined varying spacing between said lapping member and. saidlapping plate as' the supporting members are worn away means for adjusting the position of said supporting members,`and a retaining: lmember associated with said lapping membenfor confining a work piece within the lapping area of said lapping surface.

10. In a lapping apparatus having a lapping plate provided with a lapping surface,- a lapping member movable on said lapping surface of said lapping plate during a lapping operation, and

of said stationary' lapping ,memberl during a Y said l'lapping members, and means mounted on one of said lapping members for conning a work piece within the lapping area of said member and for moving said work piece relative to said other member. l

6. A lapping apparatus comprising a stationary lapping member having av lapping surface, a movable lapping member movable on said lapa plurality of supporting members capable of being worn away during the lapping operation projecting from said lapping member to engage i the lapping surface of said lapping plate and to provide a predetermined varying spacing between said lapping member and said lapping plate as said supporting members are worn away.

Brannon) s'roiin 

